Threading machine with collapsible tap having means to permit replacement of cutter bits



Filed Sept. 24, 1959 July 3, 1962 E. J. HRADEK ETAL.

THREADING MACHINE WITH COLLAPSIBLE TAP HAVING M T0 PERMIT REPLACEMENT OF CUTTER BITS BANS 3 Sheets-Sheet 1 IN V EN TORS EDWARD J. HRA DEK, HARRY W. BROWN, SR.

ATTORNEYS y 1962 E. J. HRADEK ETAL 3,041,641

THREADING MACHINE WITH COLLAPSI-BLE TAP HAVING MEANS TO PERMIT REPLACEMENTOF CUTTER BITS Filed Sept. 24, 1959 3 Sheets-Sheet 2 IN V EN TORS EDWARD J.HRADEK, y HARRY W. BROWN,SR.

ATTORNEYS Fig. 2

y 1962 E. J. HRADEK ETAL 3,041,641

THREADING MACHINE WITH COLLAPSIBLE TAP HAVING MEANS TO PERMIT REPLACEMENT OF CUTTER BITS Filed Sept. 24, 1959 3 Sheets-Sheet 3 LUB.

l I00 l F INVENTORS EDWARD J. HRADEK- y HARRY w. BRowN,R.

ATTORNEYS United States Patent 3,041,641 THREADING MACHINE WITH COLLAPSIBLE TAP HAVING MEANS T0 PERMIT REPLACEMENT OF CUTTER BITS Edward J. Hradek, Cleveland, and Harry W. Brown, Sr.,

Willowick, Ohio, assignors to The National Acme Company, a corporation of Ohio Filed Sept. 24, 1959, Ser. No. 842,148 12 Claims. (Cl. -145) The invention relates in general to threading machines and more particularly to a taper threading machine which has provision for quick and easy removal of the thread forming tools.

Threading machines of the collapsible type have been used for many years and these are the type wherein after the threading operation, the thread forming tools are laterally moved out of engegement with the workpiece so that the workpiece and thread forming tools need not be unthreaded, rather they may merely be axially separated because the thread forming tools have moved laterally out of engagement with the workpiece. Another form of threading machine is a machine for forming a taper thread, such as a pipe thread, as distinguished from a machine thread which has a constant pitch diameter. Such taper threading devices have some means of moving the thread forming tools laterally away from the workpiece during the thread forming operation, so as to form a tapered thread.

An object of the present invention is to provide a threading machine wherein the thread forming tools may quickly and easily be released from the threading machine so that they may be sharpened or replaced by tools which effectively thread a different diameter. This removal of the thread forming tools or chasers has been very difiicult in the past, especially where complicated with mechanism to perform taper threading operations.

Accordingly, the present invention incorporates three different distinct movements in a threading machine. The first, to provide lateral movement of the thread forming tools or chasers so as to form a taper thread; second, to perform a rapid withdrawal of the chasers at the end of the threading operation to perform a collapsing movement; and third, to perform an additional movement within the machine to disengage the chasers from dovetail slots or other inter-engaging surfaces so as to permit complete removal of the chasers from the threading machine. 7

An object of the invention is to provide a threading machine incorporating limit means actuated at the completion of threading operations to collapse the chasers in the machine and also to permit an additional collapsing movement to permit withdrawal of the chasers.

Another object of theinvention is to provide first and second fiuid motors in a tapping machine or threading machine to perform separate operations of collapsing the chasers and to permit complete withdrawal of the chasers.

Another object of the invention is to provide a selfcontained head which may be rotated to tap a hollow workpiece and which self-contained head also includes air cylinders to collapse the tap and to permit withdrawal of chasers from the tap.

Still another object of the invention is to provide a taper threading machine which incorporates a taper control lever which transmits three different movements through the machine, including the slow taper lateral movement of the chasers for taper threading, the quick lateral move ment of the chasers for a collapsing movement, and a still further lateral movement of the chasers to permit complete withdrawal thereof.

Other objects and a fuller understanding of the invention may be had by referring to the following de- 3,041,641 Patented Jul 3, 1962 scription and claims, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a vertical, longitudinal, sectional view of the tapping machine;

FIGURE 2 is a partial sectional view on line 2-2 of FIGURE 1;

FIGURE 3 is a bottom view of the rotating head of the tapping machine; and

FIGURE 4 is a schematic diagram of the operating circuit of the machine.

FIGURES 1, 2 and 3 show a threading machine 10 illustrated as a tapping machine, which, in this embodiment, is disposed on a vertical axis 11. This threading machine is adapted for threading a workpiece '12 which has been illustrated as a hollowworkpiece for tapping an internal thread 13. The workpiece 12 may be held in and moved axially by suitable means, such as a chuck 14.

The tapping machine 10 includes generally a frame 16, which, in this embodiment, is stationary and has bearings 17, one of which is shown, journalling a spindle 18. Gear means 19 are provided on the spindle to rotate this spindle for the threading operations. A tap housing 20 is 'slidably keyed in the spindle 18 by a key 21. This permits sliding movement of the tap housing 20 relative to the spindle 18, yet the housing 20 rotates with the spindle I8 I A trip sleeve or trip member 24 is coaxially disposed within the tap housing 20 and may axially slide therewithin. A tap body 25 is fixedly attached at the rear end of the spindle 18 to this spindle andextends coaxially inside the trip sleeve 24. A nosepiece 26 is attached to the a front end of the tap body 25 and coaxially supports a corepiece 27. The corepiece 27 has conical dovetail slots 28 to inter-engage with a plurality of chaser blocks 29. In this case, three such chaser blocks are used equidistantly spaced on the nosepiece 26, as best shown in FIGURE 3. The chaser blocks 29 carry chasers or thread forming tools 30. These chasers are shown as thread cutting chasers although they might be thread rolling tools. The chaser blocks inter-engage with radial dovetail slots 31 in order to hold these chaser blocks on the nosepiece 26. The dovetail slots 28 and 31 may be any form of inter-engaging surfaces permitting sliding movement along a path, yet preventing disengagement of the two parts in a direction perpendicular to this path. The conical dovetail slots 28 are a form of sloping interengaging surfaces which are cam surfaces, sinceupon axial movement of the corepiece 27, these chaser blocks 29 will move radially. These conical dovetail slots are termed conical because the plurality of such slots, in this case three in numbeniare disposed on a reference cone, even though all surfaces defining the slots may preferably be planarsurfaces.

The. corepiece 27 is mounted on an adjusting stud 35 which extends into a splined connection with a splined shaft 36. The splined shaft '36 has a splined connection with a corepiece shank 37 and a lock screw 39 and a retaining nut 40 adjnstably position and lock the axial position of the corepiece 27 relative to the corepiece shank 37. This is for adjustment purposes so'that the correct cutting diameter of the chasers 30 may be obtained. Once the correct adjustment is made and locked by the lock screw 39 and retaining nut 40, then the corepiece 27 and corepiece shank 37 move axially as a unit. Such movement effects radial or lateral movementt of the chasers 30 by means of the conical dovetail slots 28.

A yoke 43 is fastened to the trip sleeve 24 by any suitable means, such as bolts 44. A taper control lever 47 has first and second ends 48 and 49. The first end 48 is pivotally connected by a swivel pin 50 to the tap housing 20. The second end 49 has a pivotal connection with the yoke 43 at the swivel disc 51 which has been made large two. drawback arms 55 which are mounted in transverse slots 56 in the corepiece shank 37. Clamps 57 retain the drawback arms 55 to'the corepiece shank 3-7.

An engagement ring 60 is fixed to the front of the counterbalance bracket 63 whichisa non-rotatable part of the threading machine. A trip ring 61 is attached to the engagement ring and is adapted to engage the workpiece 12, and may be changed to accommodate workpieces of different diameters. Counterbalanc'e cylinders 62 are connected to the counterbalance bracket 63 to counterbalance most of the weight of the tap housing and other parts thereon.

A wear plate 64 is fixed to the front of the tap housing 20. This wear plate 64 may be of suitable material to resist wear caused by relative-rotation between engagement ring 60 and this wear plate.

The above construction accommodates the taper threading structure because as the chuck-14 moves the workpiece 12 axially upwardly, the workpiece moves the tap housing 20 upwardly and this recedes the swivel pin 50 a wardly. Thus, it will be seen that as the workpiece and chasers axially move relative to each other in a tapping direction, the taper controllever recedes and through its mechanical advantage of'the lever itself plus the cam surface of the conical, slots 28, the chasers move radially inwardly a small amount so that a taper thread is formed in the workpiece 12.

The upper or rear end of the tap 'body containsa stationary fluid distributor 68 which is coaxially fixed to the frame 16. A first cylinder 69 is coaxially mounted in the fluid distributor 68 and is fixed to'the tap body 25 to rotate with this tap body and the spindle 18. A first piston 70 slides inside the first cylinder 69. 'A second cylinder 72 is fixed inside'the tap body 25 below the 'first cylinder 69. A plate 73 separates the: first and second cylinders and a second piston 74 slides within the second cylinder 72 and forms first and second compartments 75 and 76 therein. Conduits are provided from the fluid distributor 68 to the first and second compartments 75 and 76 and to the'up'per or rear part of the first cylinder.

69. A flanged stop rod 77 is movable in an aperture 78 in the plate 73. As such, this stop rod 77 is abuttable with both pistons 70 and 74. A piston rod 80 connects the second piston 74 to a drawback pin'81, which, in turn, is fastened in the trip sleeve 24.

FIGURE 4 shows schematically portions of the threadin g machine 10 and shows the electrical and fluid circuits. A fluid pressure source, such as an air pressure source 85, is connected through a valve 86 and a filter 87 to a pressure regulator 88. From this pressure regulator a conduit 89 supplies a fluid under substantially constant pressure to a four-way valve shown diagrammatically at 90*. This four-way valve is actuated by a solenoid 91 between first and'second conditions, and the first condition ii is shown in FIGURE 4 when the solenoid 9l'is actuated .and with a spring 92 extended. The four-way valve has exhaust connections to a drain 93 and has first and second conduits 94 and 95 which pass through the fluid distribu tor 68 to the first and second compartments. 75 and 76, respectively, 'on either side of the second piston 74. A substantially constantfluid pressure is also supplied from the pressure regulator 88 through a conduit 98 to another taper thread tapping operations.

"pressure regulator 99 and then .by a third conduit 100 through the fluid distributor 68 to the upper endof the cylinder 69 to act on the first piston 70. A limit switch condition as actuated by a first dog 104 connected to the counterbalance cylinder piston rod to move with the tap housing 20. This first condition of the limit switch 103 is a closed contact condition to energize the solenoid 91. This first condition of the limit switch 103 is caused by completion of tapping movement when the tap housing 20 and the taper control level- 47 has moved the first distance to the receded. position. At this point the first dog actuates the limit switch 103 to the closed condition as an incidence of completion of the tapping operation. When the tap housing 20 has advanced downwardly to the position shown in FIGURE 1, then a second dog actuates the limit switch 103 to a second condition which is an oflf condition to'de-energize the solenoid 91.

Operation The threading machine 10 is shown as one which performs thread tapping operations and more particularly There must his relative axial movement between the tapping machine 10 and the workpiece and this is shown in this invention for purposes of illustration as being effected by axial movement of the workpiece 12. 'There must also be relative rotational movement betweenthe workpiece 12 and the chasers 30 and for purposes of illustration, this has been shown as being accomplished by rotation of the spindle 18. The commencement of threading operations is with the machine in the position shown in FIGURE 1. The workpiece 12 isjustin engagement with the trip ring 61 and just starting into thread forming engagement with the tools or chasers 30. The cutting diameter of the chasers has previously been set by adjusting the-position of the corepiece 27 relative to the corepiece shank 37 so that the cam surfaces of the conical dovetail slots 28 position the chaser radially to establish this pre-determined diameter. The spindle 18 isrotated through the gear means 19 and synchronously the workpiece 12 is moved upwardly axially, as by a lead screw to maintain a definite relationship between axial movement and rotation. As the workpiece 12 moves upwardly, the entire tap housing 20 moves upwardly, with the counterbalance cylinders 62 counterbalancing' most of the weight. As the tap housing 20 moves upwardly, it moves the swivel pin 50 a first distance in a receding direction to the position 50A.

This is equal to the distance which is to be threaded on the workpiece 12.. During this receding movement, the taper control lever 47 swivels on the swivel disc 51 and moves the fulcrum pin 52 a second distance in a'receding direction to the position 52A. 'This is a mechanical advantage of approximately 8:1 for the proportions shown, although this may be varied without departing from the invention. This recedes the corepiece shank 37 and corepiece 277 this same second distance by acting through the drawback arms 55. Because of the inter-engaging surfaces of the dovetail slots 31, the chaser blocks 29 are moved radially inwardly; hence, the chasers 30 are moved radially inwardly to form the tapered internal thread 13.

The fulcrum pin 52 is shown in-the hole 54, which may be spaced from the pivotcenter of the swivel disc 51, such that a pipe thread with a taper of to the foot is obtained. .If the fulcrum pin 52 is inserted in the hole 53, then may be "proportioned to establish a threadingoperation at which time the first dog 104 actu-ates the limit switch 103 to. the first condition energizing the solenoid 91v to the first condition to move the four-way valve 90 to the first condition shown. This provides fluid pressure in the first conduit 94 and into the first compartment 75 upwardly to retract the second piston 74. As seen in FIGURE 1, this retracts the piston rod 80, the drawback pin 81 and the trip sleeve 24 a third distance to retract the fulcrum pin 52 a fourth distance to a point 523. This fourth distance is nearly equal to the third distance because the taper control lever 47 at this time pivots about the first end at the swivel pin 50. This retraction through the fourth distance retracts the corepiece shank 37 and the corepiece 27 this same fourth distance and this movement takes place quite rapidly, which imparts a rapid collapsing movement to the chasers 30. This collapsing movement of the chasers 30 is rapid because it is as rapid as movement of the second piston 74. This collapsing movement of the chasers 30 permits the thread forming surfaces thereon to be completely separated from the newly formed thread on the workpiece 12, and hence, the chasers 3t) and the workpiece 12- may be axially separated without unthreading the same. This axial separating movement is shown in this case as effected by a downward movement of the workpiece 12. The weight of the tap housing 20 causes it to follow downwardly, and as the tap housing 20 reaches the downmost limit position as shown in FIGURE 1, the second dog 3185 actuates the limit switch 103, de-enengizing solenoid 91, and releasing pressure in the first compartment 75, and, instead, establishing pressure in the second compartment 76. This moves the second piston 74 rapidly downwardly to reset the entire threading machine 10 for another thread tapping operation. During the downward following movement of the tap housing 20, the swivel pin 50 has moved downwardly from the position SfiA to the full line position shown in FIGURE 1, and the movement of the second piston 74 downwardly moves the fulcrum pin 52 from the position 52A to the full line position shown in FIGURE 1.

The first cylinder 69 and piston 70 provides a third movement to the taper control lever 47 which permits radial removal of the chaser blocks 29 so that the chasers 36 may be sharpened or may be replaced with chasers of different sizes for threading a different diameter workpiece. Because of the radial dovetail slots and the conical dovetail slots 29, the chaser blocks 29 are firmly held on the nosepiece 26. To radially remove these chaser blocks, they must be disconnected at the corepiece 27 which means that this corepiece 27 must be axially moved upwardly sufficiently to disengage the conical dovetail slots 28.

With the threading machine 10 in the position which it assumes at the completion of a threading operation, which is with the tap housing 20 in its upper receded position and with the second piston 74 moved upwardly by pressure in the first compartment 75, then the fulcrum pin 52 is in the position 52B. At this time the pressure regulator 9? may be actuated manually, for example,'to reduce the pressure in the conduit 100. This normally is substantially the same pressure as applied to compartments 75 and 76 and since the upper end of the piston 76 has a larger area than the area in the second compartment 76, this means that the first piston 79 is moved downwardly to move the stop rod 77 downwardly. This prevents the second piston 74 from moving upwardly to the end of the second cylinder 72. Now with the pressure reduced at the upper end of the first piston 70, the pressure in the first compartment '75 moves the second piston 74 and the stop rod 77 upwardly a fifth distance. This retracts the piston rod 80, the drawback pin 81 and the trip sleeve 24 this same fifth distance. The taper control lever 47 pivots about the swivel pin t and, hence, the fulcrum pin 52 recedes a sixth distance to a position 52C. This recedes the corepiece 27 this same sixth distance and this is sufiicient to completely disengage the conical dovetail slots 28 on the corepiece 27 from the chaser blocks 29. Since the tap housing 20 is moved upwardly'to its upper limit, it is out of the way so that the chaser blocks 29 may then readily be removed from the nosepiece 26 for sharpening or replacement.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on said frame and having an axis, thread forming tools mounted for lateral movement on said body for threading any said workpiece, interengaging cam surfaces acting on said tools effecting lateral movement of said tools upon relative axial movement thereof, means on said frame to relatively axially and rotatively move a workpiece and said body for taper threading operations, taper control means connected between said body and said cam surfaces to eifect lateral movement of said tools in accordance with relative axial threading receding movement a first distance of said workpiece and said 'body, said first distance moving said cam surfaces axially a second distance to establish a tapered thread on any said workpiece, motive power means including a piston and cylinder in said frame, linkage means connecting said motive power means to said taper control means, limit mean having first and second conditions as actuated by relative axial movement of said workpiece and said body, means connecting said limit means to control actuation of said motive power means, completion of a threading operation moving said taper control means to the receded position whereupon said limit means is actuated to said first condition to retract said motive power means a third distance to retract one of said cam surfaces a fourth distance to laterally collapse said tools to permit axial separating movement of said tools and any workpiece without relative rotational movement therebetween, and means to retract said piston a fifth distance whereby when said taper control means is in said receded position said fifth distance permits retraction of one of said cam surfaces a sixth distance via said taper control means to release said tools at said interengaging cam surfaces to permit lateral removal of said tools from said body.

2. A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on said frame and having an axis, a corepiece coaxially and slidably mounted relative to said body, thread forming tools mounted for lateral movement on said body for threading any said workpiece, interengaging sloping surfaces acting between said tools and said corepiece elfecting lateral movement of said tools upon relative axial movement of said corepiece and said body, means on said frame to relatively axially and rotatively move a workpiece and said body for taper threading operations, taper control lever means having first and second ends, first means pivoted to said lever means first end to recede same upon relative axial threading movement of said workpiece and said body, means interconnecting said lever means second end and said corepiece so that when said lever means first end recedes a first distance during threading operations said lever means retracts said corepiece a second distance to eifect lateral movement of said tools via said interengaging sloping surfaces to establish a tapered thread on any said workpiece, motive power means and a piston and cylinder in said frame, a movable stop rod acted on by said motive power means and said piston, linkage means connecting said motive power means to said lever means second end, limit means having first and second conditions as actuated by relative connecting said limit means to control actuation of said motive power means, completion of a threading operation ,moving said lever means to the receded position ,whereupon said limit means is actuated to said first condition to retract said motive power means a third distance into engagement with said stop rod to retract said corepiece, a fourth distance to laterally collapse said tools to permit axial separating movement of said tools and, any workpiece without relative rotational movement therehetween,

, said axial separating movement actuating said limit means to said second condition to advance said motive power means said third distance to reset said machine for another threading operation, and manually responsive means to permit movement of said piston whereby when I said taper control lever means is in said receded position said motive power means is actuated rearwardly against said'stop rod to retract said stop rod and said piston a fifth distance to retract said corepiece a sixth distance via said taper control lever means pivoting at said first end i thereof and such retraction establishing release of said limit means to said second condition to advance said sec-- nd fluid motor to reset said threading machine for another operation, and manually responsive-means to actuate said first fluid motor whereby when said limit means is in said first condition said second fluid motor is movable into engagement with said stop rod .to retract said stop rod and said first fluid motor to retract said cam means a still further distance via said linkage means and such tools at said interengaging sloping surfaces to permit lat V eral removal of said tools from said body.

3. A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on said frame and having an axis, thread forming tools mounted for lateral movement on said body for threading any said workpiece,- cam and follower means connected to effect v lateral movement of said tools, means on said frame to relatively axially and rotatively move a workpiece and said body for threading operations, a piston and cylinder in said frame, motive power means, linkage means connecting said motive power means to said cam means,

limit means having first and second conditions as actuated by relative axial movement of said workpiece and said body, fluid pressure means connected to said cylinder to move said piston to an advanced position, completion of a threading operation actuating said limit means to said first condition to retract said motive power means into engagement with said piston to retract said cam means to laterally collapse said tools to permit axial separating movement of said tools and any workpiece without relative rotational movement therebetween, said axial separating movement actuating said limit means to said second condition to advance said motive power means to reset said threading machine for another operation, and manually responsive means to relieve said fluid pressure means whereby when said limit means is in said first condition said motive power means is movable into engagement with said piston to retractsaid cam means a still further distance via said linkage means and such retraction establishing release ofsaid tools at said cam means to permit lateral removal of said tools from said body;

4. A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on said frame and having an'axis, thread forming tools mounted for lateral movement on said body for threading any said workpiece, cam and followermeans connected to effect lateral movement of said tools, means on said frame to relatively axially and rotatively move a workpiece and said body for threading operations, first and second fluid motors in said frame, a movable stop rod, means connecting said first and second fluid motors to act on said stop rod, linkage means connecting said second fluid motor to said cam means, limit means having first and second conditions as actuated by relative axial movement of said workpiece and said body, means connected to said first fluid motor to move said stop rod to an advanced position, completion of a threading operation actuating said limit means to said first condition to retract said second fluid motor into engagement with said stop rod to retract said corepiece to laterally collapse said tools to permit axial separating movement of said tools and any 7 workpiece without relative rotational movement there between, said axial separating movement actuating said retraction establishing release of said tools to permit lateral removal of said tools from said body.

5. A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on said frame and having an axis, a corepiece coaxially and slidably mounted relative to said body, thread forming tools mounted for lateral movement on the front of said body for threading any said workpiece, conical dovetail slots on said corepiece effecting lateral movement of said tools upon relative axial movement of said corepiece and said body, means on said frame to relatively axially and rotatively move a workpiece and said body for threading operations, first and second cylinders in said frame, first and second pistons moveable inside said first and second cylinders, respectively, said second piston dividing said second cylinder into first and second compartments, a stop rod movable in said second compartment abuttable with said second piston, means connecting said first piston to act on said stop rod, linkage means including a piston rod connecting said second piston to said corepiece, valve means having first and second conditions as actuated by relative axial movement of said workpiece and said body, a fluid pressure source connected to said valve means, first and second conduits connected from said valve means to said first and second compartments of said second cylinder, respectively, fluid pressure means connected to one end of said first cylinder to exert an advancing force on said first piston to move said stop rod to an advanced position, completion of a threading operation actuating said valve means to said first condition to establish pressure in said first compartment to retract said second piston into engagementwith said stop rod to retract said corepiece to laterally collapse said tools to permit axial separating movement of said tools and any workpiece without relative rotational movement therebetween, said axial separating movement actuating said valve means to said second condition to establish pressure in said second compartment to advance said second piston to reset said threading machine for another operation, and manually actuated means to effect reduction of pressure on said one end of said first piston whereby when said valve means is in said first condition the pressure in said first compartment moves said second piston rearwardly against said stop rod to retract said stop rod and said first piston to retract said corepiece a still further distance via said linkage means and such retraction establishing release of said tools at said conical dovetail slots to permit lateral removal of said tools from said body. 7

6. A threading machine for threading a workpiece comprising, in combination, a frame, --a body mounted on said frame and having an axis, a corepiece coaxially and slidably mounted in said body, thread forming tools mounted for radial movement on the front of said body for threading any said workpiece, conical dovetail slots on said corepiece elfecting radial movement of said tools upon relative axial movement of said corepiece and said body, means on saidframe'to relatively axially and r0 tatively move a workpiece and said body for threading operations, first and second cylinders in said frame, first and second pistons movable inside said first and second cylinders, respectively, said second piston dividing said second cylinder into first and second compartments, a stop rod'movable in said second compartment abuttable switch means having first and second conditions as actu- 9 a ated by relative axial movement of said workpiece and said body, a solenoid actuated four-way valve connected for actuation to first and second conditions, respectively,

actuated means to ettect reduction of pressure in said by the first and second conditions of said limit switch 1 means, a fluid pressure source and an exhaust connected to said four-way valve, first and second conduits connected from said four-way valve to said first and second compartments of said second cylinder, respectively, a

third conduit connected from said fluid pressure source to one end of said first cylinder to exert an advancing force on said first piston to move said stop rodto an advanced position, completion of a threading operation actuating said limit switch means to said first condition to establish pressure in said first compartment to retract said second piston into engagement with said stop rod to retract said corepiece to radially collapse saidtools to permit axial separating movement of said tools and any workpiece without relative rotational movement therebetween, said axial separating movement actuating said limit switch means to said second condition to establish pressure in said second compartment to advance said second piston to reset said threading machine for another operation, and manually actuated means to eifect reduction of pressure in said third conduit from said pressure source to reduce the pressure on said one end of said first piston whereby when said limit switch means is in said first condition the pressure in said first compartment moves said second piston rearwardly against said stop rod to retract said stop rod and said first piston to retract said corepiece a still further distance via said linkage means and such retraction establishing release of said tools at said conical dovetail slots to permit radial removal of said tools from said body.

7. A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on said frame and having an axis, a corepiece coaxially and slidably mounted in said body, chasers mounted for radial" movement on the front of said body for threading any said workpiece, conical dovetail slots on said corepiece effecting radial movement of said chasers upon relative axal movement of said corepiece and said body, means on said frame to relatively axially and rotatively move a workpiece and said body for threading operations, first and second cylinders in said frame, first and second pistons axially movable inside said first and second cylinders, respectively, said second piston having a smaller area than said first piston, a plate separating said cylinders, a stop rod axially movable in an aperture in said plate and abuttable with each of said pistons, linkage means including a piston rod connecting said second piston to said corepiece, limit switch means having first and second conditions as actuated by relative axial movement of said workpiece and said body, a solenoid actuated four-way valve connected for actuation to first audsecond conditions, respectively, by the first and second conditions of said limit switch means, a fluid pressure source and an exhaust connected to said four-way valve, said second piston dividing said second cylinder into first and second compartments, first and second conduits connected from said four-way valve to said first and second compartments of said second cylinder, respectively, a third conduit connected from said fluid pressure source to the rear end of said first cylinder to exert an advancing force on said first piston to move said stop rod to an advanced position, completion of a threading operation actuating said limit switch means to said first condition to establish pressure in said first compartment to retract said second piston into engagement with said stop rod to retract said corepiece to radially collapse said chasers to permit axial separating movement of said chasers and any workpiece without relative rotational movement therebetween, said axial separating movement actuating said limit switch means to said second condition to establish pressure in said second compartment to advance said second piston to reset said threading machine for another operation, and manually third conduit from said pressure source to reduce the pressure on the rear end of said first piston whereby when said limit switch means is in said first condition the pressure in said first compartment moves said second piston rearwardly against said stop rod to retract said stop rod and said first piston to retract said corepiece a still further distance via said linkage means and such retraction establishing release of said chasers at said conical dovetail slots to permit radial removal of said chasers from said body. I

8. A tapping machine for tapping a workpiece comprising, in combination, a frame, a tap body mounted on said frame and having an axis, a corepiece co-axially and slidably mounted in said tap body,.c has ers mounted for radial movement on the front of said tap body for thread tapping any said workpiece, conical dovetail slots on said corepiece effecting radial movement of said chasers upon relative axial movement of said corepiece and said tap body, means on said frame to relatively axially and rotatively move a workpiece and said tap body for thread tapping operations, first arid second cylinders in said frame, first and second pistons axially movable inside said first and second cylinders, respectively, said second piston having a smaller area than said first piston, a plate sepaaxial movement of said workpiece and said tap body, a V

solenoid actuated four-Way valve connected for actuation to first and second conditions, respectively, by the first and second conditions of said limit switch means, a fluid pressure source and an exhaust connected to said fourway valve, said second piston dividing said second cylinder into first and second compartments, first and second conduits connected from said four-way valve to said first and second compartments of said second cylinder, respectively, a third conduit connected from said fluid pressure source to therear end of said first cylinderto exert an advancing force on said first piston to move said stop rod to an advanced position, completion of a tapping operationactuating said limit switch means to said first condition to establish pressure in said first conduit to retract saidsecond-piston into engagement with said stop rod to retract said corepiece to radially inwardly collapse said chasers to permit axial separating movement of said chasers and any workpiece without relative rotational movement therebetween, said axial separating movement actuating said limit switch means to said second condition to establish pressure in said second conduit to advance said second piston to reset said tap for another tapping operation, and manually actuated means to effect reduction of pressure in said third conduit from said pressure source to reduce the pressure on the rear end of said first movement of said chasers from said tap body.

9. A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on said frame and having an axis, thread forming tools mounted for lateral movement on said body for threading any said workpiece, means on said frame to relatively axially and rotatively move a workpiece and said body for taper threading operations, taper control means connected to eifect lateral movement of said tools in accordance with relative axial threading receding movement a first distance of said workpiece and said body, said first distance moving said taper control means a second dismeans elfective upon completion of a threading operation to'laterally collapse said tools to permitaxial'separating' movement of 'saidrtools and any workpiece without relative rotational movement therebetween, motive power means connected to said'taper control means, and manually responsivemeans to permit movement of said motive power means a third distance to retract said taper control lateral removal of said tools from said body.

' "103A threading machine for threading a workpiece comprising, in combination, a frame, a body mounted on sa1d frame and having an axis, thread forming tools mounted for lateral movement on said body for threading any said workpiece, means on said frame to relatively axially and r'otatively move a workpiece and said body for taper threading operations, taper control means connected to effect lateral movement of said tools in accordmeans a fourth distance to releasesaidlto ols to permit ance with relative axial threading receding movement a first distance of said workpiece and said body, said first distance moving said taper control means a second distanceto establish'a tapered thread on any said workpiece, motive power means in said frame, linkage'means connecting said motive power means to 'said taper control means,"limit means eifective upon completion of a threading operation to retract said motive power means a third distance to retractsaid taper control means a fourth distance to laterally collapse said tools to permit axial separating movement of said tools and any workpiece without relative rotational movement therebetween, and

manually responsive means to permit movementof said motive power. means a fifth distance to retract said taper control means a sixth distanceto release said tools to [permit lateralremoval of said tools from said body.

11.".A threading machine for threading a workpiece taper threading operations, taper control means connected to etfect lateral movement of said tools in accordance with relative axial threading receding movement a first distance of said workpiece and said body, said first distance "comprising, in combination, a frame, a body mounted on moving said taper control means a second distance to second motive powermeans in said frame, linkage means connecting said first and second motive power means to establish a tapered thread on any said workpiece, firstand power means a third distance jto retract said taper control means "a fourth distance to laterally collapse said tools to permit axial separating, movement of said tools and any workpiece without relative rotationl movement therebetween, and manually'responsive means to permit movement of said second motive power means a fifth distanceto retract said taper control means a sixth distance to release said toolsto permit lateral removal of said tools from said body. 7

12.. A threading machine for threading a workpiece comprising'in combination, a frame, a body mounted on said frame and having an axis, thread forming tools mounted for lateral movement on said body for threading any said workpiece, interengaging cam surfaces acting on said tools effecting lateral movement of 'said'tools upon relative axial movement of said cam surfaces, means on said frame to relatively axially and rotatively move a workpiece and said body for taper threading operations, taper control means connected tosai'd cam surfaces to effect lateral'movement of said tools in accordance with relative axial threading receding movement a first distance of said workpiece and said body, said first distance moving said camsurfaces axially a second distance to establish a tapered thread on anysaid workpiece, first and second motive power meansin said frame, linkage means connecting said first and second motive'power means to said taper control means, limit means effective upon completion of a threading operation to retract said first motive power'means a third distance to retract said cam surfaces a fourth distance to laterally collapse said tools to permit axial separating movement ofsaid tools and any'workpiece without relativer'otational movement therebetween, "andmanually responsive means 'to permit movement of saidsecond motive power'means a fifth distancewhereby when said taper control means is in said receded position said fifth distance retracts said cam surfaces a sixth distance via said taper control means to release said tools at said interengaging cam surfaces to permit lateral removal of said tools from said'body.

References Cited in the file of this patent UNITED STATES PATENTS Drissner Dec. 17, 1935 2,324,879" Robertson July 20, 1943 2,746,066 Fin May 22, 1956 

